To determine the incidence of hepatitis in prospectively followed open heart surgery patients receiving blood that has been pre- screened for donor transaminase (ALT) level and since 1986, for anti-core (anti-HBc) antibody. Blood units with elevated ALT or anti-HBc will be discarded. Hepatitis incidence will be compared with that of identically followed patients in previous studies in which no attempts was made to exclude blood with these surrogate markers. In previous studies blood units with elevated ALT or anti-HBc were more frequently associated with recipient hepatitis than units with normal values. Cases of hepatitis will be serologically assessed for virus etiology and patients will be carefully followed for the development of chronic hepatitis.